1. Field of the Invention
The present invention relates to the field of imaging internal portions of animal bodies.
2. Description of the Background Art
Images of internal structures and organs within a patient can be utilized for performing diagnosis and monitoring of patients. Such internal images can be obtained, for example, by ultrasonic imaging, magnetic resonance imaging (MRI) and optical imaging.
Ultrasonic images are formed utilizing reflected ultrasound waves, which are detected and electronically converted into a visual display.
Ultrasonic imaging is particularly desirable when the internal structures of interest within the patient can be imaged utilizing the reflected ultrasound alone. However, it sometimes is necessary to enhance the contrast of an ultrasound image by introducing a contrast agent into the patient. Heretofore, such ultrasound contrast agents typically have been introduced into patients by injection. Unfortunately, injection of an ultrasound contrast agent into a patient destroys the otherwise non-invasive advantage of ultrasonic imaging.
Other types of internal imaging, such as MRI and optical imaging, often also require injection of contrast agents to enhance the images.
PCT International Publication No. WO 93/06869 to Vanderripe proposed inhalation of various gases to produce supersaturation in the blood for ultrasound contrast.
Contrast enhanced magnetic resonance imaging of the airways of the lungs has been proposed using aerosolized gadopentetate dimeglumine in Radiology, 183: 667-672 (1992). However, there is no suggestion of delivery of contrast agent into the pulmonary circuit for MRI enhancement of non-lung tissue.
There remains a need in the art for methods and compositions for enhancing contrast during internal imaging of non-lung tissue in patients, without the need for invasively injecting a contrast agent into the patient.